how do excessive curvature of the eye lens and elongation of eyeball contributes in myopia???explain in detail.
Answers
Myopia is often referred to as ‘nearsightedness’ or ‘short-sightedness’ and is the most common refractive error of the eye. Generally Myopia appears at the age of 8 years and becomes worse until age of 20. In people with normal vision, eyeball grows with other parts of the body and stops growing at a point when it seems to have clear vision. But in people with Myopia the eyeball becomes elongated and takes the shape of a grape or an olive. People whose parents are nearsighted may be more likely to get the condition as its genetically linked also.
Myopia typically begins in childhood and you may have a higher risk if your parents are nearsighted. In most cases, nearsightedness stabilizes in early adulthood but sometimes it continues to progress with age.
Myopia Treatment
Nearsightedness can be corrected with glasses, contact lenses or refractive surgery. Depending on the degree of your myopia, you may need to wear your glasses or contact lenses all the time or only when you need very clear distance vision, like when driving, seeing a chalkboard or watching a movie.
Good choices for eyeglass lenses for nearsightedness include high-index lenses (for thinner, lighter glasses) and anti-reflective coating. Also, consider photochromic lenses to protect your eyes from UV and high-energy blue light and to reduce your need for a separate pair of prescription sunglasses outdoors.
If you're nearsighted, the first number ("sphere") on your eyeglasses prescription or contact lens prescription will be preceded by a minus sign (–). The higher the number, the more nearsighted you are.
Controlling Myopia
With more and more people getting nearsighted these days, there is a lot of interest in finding ways to control the progression of myopia in childhood.
A number of different techniques have been tried — including fitting children with bifocals, progressive lenses and gas permeable contact lenses — with mixed results.
Recently, researchers in New Zealand have reported encouraging outcomes from specially designed "dual focus" soft contact lenses for myopia control in nearsighted children. The experimental lenses have significantly less power in the periphery of the lens compared to the center, and it is thought that this "peripheral defocus" may reduce the tendency for greater lengthening of the eye that leads to progressive myopia.
In a study published in 2011, the researchers found that in 70 percent of nearsighted children (ages 11 to 14) who wore the experimental lenses in one eye and a standard soft contact lens in the other, myopia progression was reduced by 30 percent or more in the eye wearing the dual focus contact lens.
Though dual focus contact lenses for myopia control are not yet available in the United States, research is ongoing to evaluate the effectiveness of the lenses on a larger population of children.
